Where does the term jet-black come from?

This phrase comes from the stone "jet." Jet is a black stone used in jewelery, so "jet-black" refers to the color of the stone
Middle English, from Anglo-Norman geet, from Latin gagts, from Greek, after Gagas, a town of Lycia.]adj.Made of or resembling a dense, black, highly polished coal.Black as coal; jet-black: jet hair.
Above taken from Dictionary.com
Viper1

This phrase comes from the stone "jet." Jet is a black stone used in jewelery, so "jet-black" refers to the color of the stone
Middle English, from Anglo-Norman geet, from Latin gagts, from Greek, after Gagas, a town of Lycia.]adj.Made of or resembling a dense, black, highly polished coal.Black as coal; jet-black: jet hair.
Above taken from Dictionary.com
Viper1